Barium titanate BaTiO3

spore: profile
id: barium-titanate
spore_version: 0.2
family: oxide-ceramics
name: Barium titanate
abbreviation: BaTiO3
role: ferroelectric, piezoelectric and high-permittivity perovskite ceramic
category: ceramics
type: oxides
summary: |
  Barium titanate (BaTiO3) is a white perovskite oxide. It is a ferroelectric ceramic with a high dielectric constant, and it is used as the dielectric in multilayer ceramic capacitors (MLCCs) and as a lead-free piezoelectric ceramic. A supplier safety data sheet gives its melting point as 1625 °C. A 2015 study of reactively sintered ceramics gave a Curie temperature of about 125 to 128 °C and a piezoelectric constant d33 of about 120 pC/N. A supplier datasheet for a single crystal gives its tetragonal phase as running up to 132 °C. A 2024 study measured single nanopowders and found a peak dielectric constant of 60 at about 55 nm.
best_for: Capacitor dielectrics and lead-free piezoelectric ceramics where operation stays well below the Curie point of about 125 to 132 °C
weakest_at: 'Temperature range: the ferroelectric response is lost above about 125 to 132 °C, and a reactively sintered ceramic reached only about 85% relative density in the 2015 study'
identity:
  formula: BaTiO3
  cas: 12047-27-7
  crystal_system: tetragonal
  source: sa-ba1287
  where: Stanford SDS section 1 (CAS No 12047-27-7) and section 9 (molecular formula BaO3Ti, molecular weight 233.24); tetragonal structure from the single-crystal datasheet (surfacenet-bto); PubChem CID 159419 gives molecular weight 233.19
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - electronics-and-chips
    - mechanisms
properties:
  - benchmark: density
    label: Relative density, barium titanate powder (Apollo SDS)
    value: 6.08
    unit: '-'
    scope: material
    conditions:
      form: solid powder
      reference: relative to water (water = 1)
    method: Value printed as relative density in a supplier safety data sheet; no g/cm3 unit is printed
    status: ground
    source: apollo-in1226
    where: Section 9.1, Relative density (Water = 1)
  - benchmark: density
    label: Density, single crystal
    value: 6.06
    unit: g/cm3
    scope: material
    conditions:
      form: single crystal grown by top-seeded solution growth
      temperature: 26 °C
    method: Value printed on a supplier crystal datasheet
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Density row
  - benchmark: melting_point
    label: Melting point, powder (Stanford SDS)
    value: 1625
    unit: °C
    scope: material
    conditions:
      form: powder, product BA1287
    method: Value printed in a supplier safety data sheet (also printed as 2957 °F)
    status: ground
    source: sa-ba1287
    where: Section 9, Melting Point/Range
  - benchmark: melting_point
    label: Melting point, single crystal
    value: 1891
    unit: K
    scope: material
    conditions:
      form: single crystal grown by top-seeded solution growth
    method: Value printed as 1891 K on a supplier crystal datasheet
    status: ground
    note: 1891 K is about 1618 °C, a few degrees below the powder figure from the Stanford sheet.
    source: surfacenet-bto
    where: Crystal properties table, Melting Point row
  - benchmark: curie_temperature
    label: Curie temperature, reactively sintered ceramic
    value: 125
    value_high: 128
    bound: range
    unit: °C
    scope: material
    conditions:
      form: reactively sintered BaTiO3 ceramics, sintered at 1200 to 1400 °C
      test: dielectric constant against temperature at 10 kHz
    method: Temperature of the dielectric peak measured with an impedance analyzer
    status: ground
    note: The text layer prints the range with a superscript-three approximation symbol before it, so read it as approximate.
    source: kawashima2015
    where: Section 3, dielectric constant against temperature (Fig. 5b text)
  - benchmark: curie_temperature
    label: Upper limit of the tetragonal phase, single crystal
    value: 132
    unit: °C
    scope: material
    conditions:
      form: single crystal grown by top-seeded solution growth
      phase: tetragonal structure from 13 °C to 132 °C
    method: Phase range printed as crystal structure on a supplier datasheet; its upper limit is used as the transition temperature
    status: ground
    note: The datasheet prints a temperature range for the tetragonal structure rather than the word Curie.
    source: surfacenet-bto
    where: Crystal properties table, Crystal Structure row
  - benchmark: dielectric_constant
    label: Relative permittivity along the a axis, single crystal
    value: 3000
    unit: '-'
    scope: material
    conditions:
      form: single crystal, a axis
      temperature: not stated on the page
    method: Value printed on a supplier crystal datasheet; the symbols are garbled in the text layer
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Dielectric constant row (epsilon a)
  - benchmark: dielectric_constant
    label: Relative permittivity along the c axis, single crystal
    value: 800
    unit: '-'
    scope: material
    conditions:
      form: single crystal, c axis
      temperature: not stated on the page
    method: Value printed on a supplier crystal datasheet; the symbols are garbled in the text layer
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Dielectric constant row (epsilon c)
  - benchmark: dielectric_constant
    label: Relative permittivity quoted in an introduction (literature)
    value: 1700
    unit: '-'
    scope: material
    conditions:
      form: BaTiO3, sintered form and frequency not stated
    method: Value quoted from earlier work in the introduction of a 2015 paper; not measured by the authors
    status: ground
    source: kawashima2015
    where: Section 1 (Introduction), first paragraph
  - benchmark: dielectric_constant
    label: Peak relative permittivity, single nanopowder
    value: 60
    unit: '-'
    scope: material
    conditions:
      form: single BaTiO3 nanopowder of about 55 nm
      method: scanning dielectric microscopy on individual particles
    method: Peak value reported in the abstract of a 2024 study; measured on single particles, not in a slurry
    status: ground
    note: Earlier slurry methods combined the powder and the solvent, so this figure is not comparable with bulk ceramic values.
    source: skku-nanopowder
    where: Abstract
  - benchmark: piezoelectric_d33
    label: Piezoelectric constant d33, reactively sintered ceramic
    value: 120
    unit: pC/N
    scope: material
    conditions:
      form: reactively sintered BaTiO3 ceramic, sintered at 1300 °C for 2 h
      density: about 85% relative density
    method: d33 measured with a d33 meter 24 h after poling
    status: ground
    note: The text layer prints the value with the same approximation symbol, so read it as about 120.
    source: kawashima2015
    where: Abstract; Section 3, d33 against sintering temperature (Fig. 6)
  - benchmark: relative_density
    label: Relative density, reactively sintered ceramic
    value: 85
    unit: '%'
    scope: material
    conditions:
      form: reactively sintered BaTiO3 ceramic
      sintering: about 1250 °C and above; the 1250 and 1300 °C samples had similar densities
    method: Density from mass and dimensions, averaged over two samples
    status: ground
    note: Printed with an approximation symbol. The same paper gives about 72% at 1200 °C.
    source: kawashima2015
    where: Abstract; Section 3, relative density (Fig. 2 text)
  - benchmark: thermal_conductivity
    label: Thermal conductivity, single crystal
    value: 6
    unit: W/mK
    scope: material
    conditions:
      form: single crystal
      temperature: 300 K (printed as 300 °K)
    method: Value printed on a supplier crystal datasheet (printed as W/m k)
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Thermal conductivity row
  - benchmark: specific_heat
    label: Specific heat, single crystal
    value: 0.527
    unit: J/gK
    scope: material
    conditions:
      form: single crystal
      temperature: 300 K (printed as 300 °K)
    method: Value printed on a supplier crystal datasheet (printed as J/g k)
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Specific Heat row
  - benchmark: cte
    label: Thermal expansion along the a axis, single crystal
    value: 15.7
    unit: ppm/K
    scope: material
    conditions:
      form: single crystal, a axis
      temperature_range: not stated on the page
    method: Printed as 10 -6 per K on a supplier crystal datasheet; the symbols are garbled in the text layer
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Thermal expansion row (a)
  - benchmark: cte
    label: Thermal expansion along the c axis, single crystal
    value: 6.2
    unit: ppm/K
    scope: material
    conditions:
      form: single crystal, c axis
      temperature_range: not stated on the page
    method: Printed as 10 -6 per K on a supplier crystal datasheet; the symbols are garbled in the text layer
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Thermal expansion row (c)
  - benchmark: refractive_index
    label: Ordinary refractive index, single crystal at 633 nm
    value: 2.416
    unit: '-'
    scope: material
    conditions:
      form: single crystal
      wavelength: 633 nm
      ray: ordinary
    method: Value printed in a supplier datasheet table
    status: ground
    source: surfacenet-bto
    where: Index of refraction table, n o row, 633 nm column
  - benchmark: refractive_index
    label: Extraordinary refractive index, single crystal at 633 nm
    value: 2.363
    unit: '-'
    scope: material
    conditions:
      form: single crystal
      wavelength: 633 nm
      ray: extraordinary
    method: Value printed in a supplier datasheet table
    status: ground
    source: surfacenet-bto
    where: Index of refraction table, n e row, 633 nm column
  - benchmark: hardness_mohs
    label: Mohs hardness, single crystal
    value: 4.5
    unit: '-'
    scope: material
    conditions:
      form: single crystal
    method: Value printed on a supplier crystal datasheet
    status: ground
    source: surfacenet-bto
    where: Crystal properties table, Hardness (Mohs) row
corrosion:
  - environment: Strong acids and strong oxidizing agents
    headline: The SDS lists strong acids and strong oxidizing agents as incompatible. No corrosion rate or test was found.
    effect: The Stanford Advanced Materials sheet lists strong oxidizing agents and strong acids as incompatible materials and gives no rate or test result. It also states that the product is insoluble in water.
    rating: unknown
    conditions:
      basis: incompatibility list in a supplier SDS; no test
      form: powder
    source: sa-ba1287
    where: Section 10 (Incompatible materials); Section 9 (Water solubility)
  - environment: Water and humidity
    headline: The powder is insoluble in water, but no humidity-ageing test was found.
    effect: The Stanford sheet gives water solubility as insoluble and says the material is not likely to be mobile in the environment because of its low water solubility. No study of the change in dielectric or piezoelectric properties after humid storage was found in a source read in this run.
    rating: unknown
    conditions:
      basis: solubility statement only
      form: powder
    source: sa-ba1287
    where: Section 9 (Water solubility); Section 12 (Mobility)
  - environment: Heat above the Curie temperature
    headline: Above the Curie point the ferroelectric and piezoelectric response is lost.
    effect: The single-crystal datasheet gives a tetragonal phase from 13 to 132 °C. The 2015 ceramic study gives a Curie temperature of about 125 to 128 °C and says the low Curie temperature limits the temperature range for piezoelectric use. This is a loss of function, not chemical corrosion.
    rating: moderate
    conditions:
      basis: phase transition temperatures from two sources
      note: functional loss only
    source: kawashima2015
    where: Section 1 (Introduction); Section 3 (Curie temperature)
risks:
  hazards:
    - text: 'Two supplier safety data sheets classify barium titanate as acutely harmful: H302 (harmful if swallowed) and H332 (harmful if inhaled), acute toxicity category 4. PubChem''s aggregated GHS record lists the substance as not classified.'
      ghs:
        - H302
        - H332
      source: apollo-in1226
      where: Section 2.1 and 2.2 (hazard statements)
    - text: The Stanford SDS gives the signal word Warning with the statement harmful if swallowed or inhaled, for the same product (CAS 12047-27-7).
      ghs: []
      source: sa-ba1287
      where: Section 2 (Label elements)
    - text: 'Rat acute toxicity from the Stanford SDS: oral LD50 above 12 g/kg, dermal LD50 above 2000 mg/kg, and inhalation LC50 of 4.89 mg/L over 4 hours.'
      ghs: []
      source: sa-ba1287
      where: Section 11 (Toxicology data for the components)
    - text: PubChem's hazards summary reads harmful by ingestion or inhalation and an irritant, citing MSDSonline, and refers to barium as the hazardous part.
      ghs: []
      source: pubchem-bto
      where: Safety and Hazards, Hazards Summary
  failure_risks:
    - mode: Loss of piezoelectric and high-permittivity response near the Curie point
      trigger: Operation above about 125 to 132 °C
      consequence: The 2015 study says the relatively low Curie temperature limits the temperature range for piezoelectric applications. Above the transition the ferroelectric phase is lost.
      severity: moderate
      source: kawashima2015
      where: Section 1 (Introduction); Section 3 (Curie temperature)
    - mode: Porosity and low density in a reactively sintered ceramic
      trigger: Reactive sintering of BaCO3 and TiO2 at 1200 °C, which leaves an open-porous body
      consequence: The study measured a relative density of about 72% at 1200 °C and about 85% at about 1250 °C and above, with closed pores at higher temperatures. The authors note that lower density lowers the dielectric constant.
      severity: moderate
      source: kawashima2015
      where: Section 3 (relative density, Fig. 2 and Fig. 4; dielectric constant discussion)
    - mode: Incomplete reaction, leaving unreacted barium carbonate
      trigger: Reactive sintering at about 900 °C
      consequence: At 900 °C the study still found unreacted BaCO3 by X-ray diffraction. Only cubic BaTiO3 was detected from 1000 to 1200 °C, so the reaction route has to be run above about 1000 °C.
      severity: low
      source: kawashima2015
      where: Section 3 (high-temperature X-ray diffraction)
    - mode: Permittivity falls with particle size near the nanoscale
      trigger: Single nanopowders of about 55 nm, against larger particles
      consequence: The 2024 study measured a peak dielectric constant of 60 at about 55 nm and attributes the size dependence to a surface cubic layer. Capacitor makers therefore cannot shrink the dielectric grains freely.
      severity: moderate
      source: skku-nanopowder
      where: Abstract
  side_effects: []
  handling:
    - text: Store in a dry, cool and well-ventilated place with the container tightly closed. Keep it apart from strong oxidizing agents and strong acids.
      source: sa-ba1287
      where: Section 7 (Storage) and Section 10 (Incompatible materials)
    - text: Avoid breathing dust and avoid dust formation. Use a particulate filter (EN 143 type) where dust may form; the Apollo sheet advises an N95 or P1 dust mask for nuisance dust.
      source: sa-ba1287
      where: Section 7 (Handling); Section 8 (Recommended filter type)
    - text: The Apollo sheet advises avoiding dust formation and dust masks for nuisance dust, and says to try to avoid creating dust conditions.
      source: apollo-in1226
      where: Section 8 (Respiratory protection)
    - text: Thermal decomposition can release irritating gases and vapours.
      source: sa-ba1287
      where: Section 5 (Fire-fighting) and Section 10 (Hazardous decomposition products)
    - text: 'Exposure limits in these sources are set for barium, not for barium titanate as such: PubChem lists 0.5 mg/m3 as barium (inhalable, soluble compounds), and Apollo gives occupational exposure band E with a limit of 0.01 mg/m3 or below.'
      source: pubchem-bto
      where: Exposure Control and Personal Protection (MAK, PEL and TLV entries); Apollo section 8 (exposure banding)
  mitigations:
    - text: Provide adequate ventilation in the storage area and for dust-forming work, as the Apollo sheet advises.
      source: apollo-in1226
      where: Section 7 (Safe handling and storage) and Section 8 (Engineering controls)
uses:
  - application: electronics-and-chips
    device: Dielectric in multilayer ceramic capacitors (MLCCs)
    example: A 2024 study notes that passive components such as MLCCs must keep shrinking, so the BaTiO3 dielectric inside them must shrink too. The study measured the dielectric constant of single BaTiO3 nanopowders for that reason.
    source: skku-nanopowder
    where: Abstract
  - application: mechanisms
    device: Lead-free piezoelectric ceramic element
    example: A 2015 study calls BaTiO3 a potential lead-free piezoelectric ceramic. Reactively sintered at 1300 °C for 2 hours, its ceramic reached a d33 of about 120 pC/N at about 85% relative density.
    source: kawashima2015
    where: Abstract; Introduction
supply:
  - subject: Barium (mined as barite)
    producers:
      - country: India
        share_percent: 34.5
        year: 2025
      - country: China
        share_percent: 25.3
        year: 2025
      - country: Morocco
        share_percent: 11.5
        year: 2025
      - country: Kazakhstan
        share_percent: 8
        year: 2025
    critical_lists: []
    recycling: 'USGS barite chapter: Recycling: None.'
    substitutes:
      - 'USGS barite chapter: there are no large-scale alternatives to barite in oil and gas drilling fluids. The chapter does not discuss electronic ceramics.'
    source: usgs-mcs2026-barite
    where: World Mine Production and Reserves table, mine production 2025 column. Shares are calculated by Space Mushroom against the printed world total of 8,700 thousand t, which excludes U.S. output (withheld). Recycling; Substitutes.
documents:
  - title: 'Stanford Advanced Materials safety data sheet: Barium titanate(IV), cat. BA1287 (revision 6, 19 December 2025)'
    type: sds
    url: https://www.samaterials.com/tds/sc/1787276055-BA1287.pdf
    year: 2025
  - title: 'Apollo Scientific safety data sheet: Barium(II) titanate(IV), product IN1226 (issued 19 August 2024)'
    type: sds
    url: https://store.apolloscientific.co.uk/storage/msds/IN1226_msds.pdf
    year: 2024
  - title: 'PubChem: Barium titanate (CID 159419), GHS and experimental properties'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/159419
    year: 2026
  - title: 'SurfaceNet: Barium titanate (BaTiO3) single-crystal datasheet'
    type: datasheet
    url: https://surfacenet.de/files/kr_Barium_Titanate.php
    year: 2026
  - title: 'Kawashima and Suzuki: High-temperature X-ray diffraction analysis and reactive sintering of BaTiO3 piezoelectric ceramics (J. Ceram. Soc. Jpn. 123, 83-85)'
    type: paper
    url: https://tsukuba.repo.nii.ac.jp/record/33658/files/JCSJ_123-1434.pdf
    year: 2015
  - title: Size dependent dielectric properties in BaTiO3 nanopowders for application of MLCC (Applied Surface Science 678, 161110)
    type: paper
    url: https://pure.skku.edu/en/publications/size-dependent-dielectric-properties-in-batiosub3sub-nanopowders-/
    year: 2024
  - title: 'USGS Mineral Commodity Summaries 2026: Barite'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf
    year: 2026
gaps:
  - No flexural strength, fracture toughness, elastic modulus or hardness for a sintered BaTiO3 ceramic was found in a source read in this run. The only hardness value is the Mohs figure for a single crystal.
  - No vacuum outgassing, radiation, thermal-vacuum or flight result for BaTiO3 was found. No space application source was read, so no environments tag is given.
  - Space group (P4mm) and atomic weights for Ba, Ti and O were not read in a primary source in this run. The recipe parts carry no atomic_weight.
  - The 2025 USGS critical-minerals status of barite and the titanium supply chain were not checked. The USGS critical-list page returned an access block, so critical_lists is left empty.
  - The sintered-ceramic density at room temperature (bulk density, not relative density) and the dielectric constant measured on a sintered ceramic at room temperature were not found in a source read in this run. The 1700 value is quoted from an introduction.
  - 'Curie temperature varies between sources: about 125 to 128 °C for a sintered ceramic (2015 study), 132 °C as the tetragonal upper limit of a single crystal, and about 130 °C in the 2015 introduction. These are kept as separate rows.'
  - No humidity or long-term ageing study for BaTiO3 was found. The corrosion entries rest on SDS incompatibility lists and on the phase transition temperatures.
  - The Sigma-Aldrich nanopowder listing, the American Elements CAS page and the Strem SDS could not be read in this run. The NIMS thermophysical dataset page needs JavaScript and was not used.
  - Hazard data rest on two supplier SDS and the PubChem summary. The SDS and PubChem classifications differ, and the Stanford sheet gives no H codes in the copy read.
  - The MLCC use rests on one 2024 nanopowder abstract, not on a capacitor datasheet or a read of a full MLCC paper.
sources:
  sa-ba1287:
    title: 'Stanford Advanced Materials: Safety Data Sheet, Barium titanate(IV), cat. BA1287'
    id: Stanford BA1287, CAS 12047-27-7, revision 6, 19 December 2025
    url: https://www.samaterials.com/tds/sc/1787276055-BA1287.pdf
    year: 2025
    kind: datasheet
    license: supplier document, linked not reproduced
  apollo-in1226:
    title: 'Apollo Scientific: Safety Data Sheet, Barium(II) titanate(IV), product IN1226'
    id: Apollo IN1226, issued 19/08/2024, CAS 12047-27-7, EC 234-975-0
    url: https://store.apolloscientific.co.uk/storage/msds/IN1226_msds.pdf
    year: 2024
    kind: datasheet
    license: supplier document, linked not reproduced
  pubchem-bto:
    title: PubChem compound record, Barium titanate (CID 159419)
    id: CID 159419; molecular formula BaO3Ti
    url: https://pubchem.ncbi.nlm.nih.gov/compound/159419
    year: 2026
    kind: database
    license: public domain (NCBI)
  surfacenet-bto:
    title: 'SurfaceNet: Barium titanate (BaTiO3) crystal properties datasheet'
    id: SurfaceNet datasheet, top-seeded solution growth single crystal
    url: https://surfacenet.de/files/kr_Barium_Titanate.php
    kind: web
    license: supplier page, linked not reproduced
  kawashima2015:
    title: High-temperature X-ray diffraction analysis and reactive sintering of BaTiO3 piezoelectric ceramics
    id: J. Ceram. Soc. Jpn. 123 [2] 83-85 (2015), University of Tsukuba repository
    url: https://tsukuba.repo.nii.ac.jp/record/33658/files/JCSJ_123-1434.pdf
    year: 2015
    kind: paper
    license: repository copy, licence not checked
  skku-nanopowder:
    title: Size dependent dielectric properties in BaTiO3 nanopowders for application of MLCC
    id: doi:10.1016/j.apsusc.2024.161110 (Applied Surface Science 678, 161110)
    url: https://pure.skku.edu/en/publications/size-dependent-dielectric-properties-in-batiosub3sub-nanopowders-/
    year: 2024
    kind: paper
    license: abstract page, full-text licence not checked
  usgs-mcs2026-barite:
    title: Mineral Commodity Summaries 2026, Barite
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wikipedia-bto:
    title: 'Wikipedia: Barium titanate (used for history, composition and the strontium titanate mention only)'
    id: English Wikipedia article, Barium titanate
    url: https://en.wikipedia.org/wiki/Barium_titanate
    year: 2026
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 19
  unreachable: 6
  caveats: 4
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs fetched in that run. Unreachable in that run: the American Elements CAS page (bot check), the Strem SDS (HTML block), the Sigma-Aldrich nanopowder listing (block), the Hiroshima repository PDF (block), the NIMS thermophysical dataset (needs JavaScript) and the USGS critical-minerals page (access block). Wikipedia was used for history, composition and the strontium titanate mention only. Caveats: the 2015 study prints its approximation symbol as a superscript three, which is read as approximate; the SurfaceNet page garbles some symbols and gives single-crystal values; the 2024 nanopowder value is a single-particle measurement; the Apollo density is relative to water, not in g/cm3.'
story:
  recipe:
    line: 'BaTiO3 is a barium titanium oxide with the perovskite structure: one barium ion and one titanium ion for every three oxygen atoms. In the 2015 study it was made by reactive sintering of barium carbonate (BaCO3) with anatase titanium dioxide (TiO2). Only the cubic BaTiO3 phase was detected from 1000 to 1200 °C.'
    parts:
      - name: Barium
        symbol: Ba
        role: The large cation in the perovskite framework. Barium is mined as barite, the barium-bearing ore in the USGS summary.
      - name: Titanium
        symbol: Ti
        role: The small cation at the centre of each oxygen octahedron. In the 2015 route it came from anatase TiO2.
      - name: Oxygen
        symbol: O
        role: Three oxygen atoms per formula unit, forming the octahedral framework.
  risk_groups:
    - title: For people
      level: 1
      verdict: Harmful if swallowed or inhaled
      lead: Two supplier safety data sheets classify barium titanate powder as acutely harmful by swallowing or breathing it in. PubChem's summary carries no GHS classification.
      points:
        - label: The powder
          line: The Apollo Scientific sheet gives H302 and H332 (acute toxicity category 4). The Stanford sheet gives the same hazards in words, with the signal word Warning.
        - label: Animal data
          line: The Stanford table gives an oral LD50 above 12 g/kg in rats, a dermal LD50 above 2000 mg/kg and an inhalation LC50 of 4.89 mg/L over 4 hours.
        - label: Exposure limits
          line: PubChem lists 0.5 mg/m3 as barium (inhalable, soluble compounds). Apollo gives an exposure band E with a limit of 0.01 mg/m3 or below. These limits are for barium.
    - title: If it fails
      lead: These results come from ceramic tests and property measurements, not from service incidents.
      points:
        - label: Heat
          line: In a single-crystal datasheet the tetragonal ferroelectric phase lies between 13 and 132 °C. In the 2015 sintered ceramic the Curie temperature was about 125 to 128 °C, which the authors say limits piezoelectric use.
        - label: Density
          line: The reactively sintered ceramic had a relative density of about 72% at 1200 °C and about 85% at 1250 °C and above. Its d33 was about 120 pC/N at 1300 °C.
        - label: Particle size
          line: In a 2024 study of single nanopowders the dielectric constant peaked at 60 at about 55 nm. The authors attribute the size effect to a surface cubic layer.
    - title: Handling and storage
      points:
        - label: Keep it dry and closed
          line: Store in a dry, cool and well-ventilated place in a tightly closed container, away from strong oxidizing agents and strong acids.
        - label: Avoid dust
          line: Avoid breathing dust. Apollo advises an N95 or P1 dust mask for nuisance dust and adequate ventilation.
        - label: In a fire
          line: Thermal decomposition can release irritating gases and vapours, according to the Stanford sheet.
  why: Barium titanate (BaTiO3) is a perovskite oxide that is ferroelectric below its Curie temperature. Its dielectric constant is high, and it is also a lead-free piezoelectric ceramic. Wikipedia records that its development as a dielectric was driven by a shortage of mica around World War II. The material is attractive for capacitors and piezoelectric elements because of its high permittivity and its piezoelectric response. Its main limit is a Curie point near 125 to 132 °C, which caps the temperature range. Strontium titanate (SrTiO3) is the related perovskite, and Wikipedia notes that BaTiO3 can form solid solutions with it.
  uses:
    - where: Multilayer ceramic capacitors
      line: A 2024 study notes that MLCCs keep shrinking, so the BaTiO3 dielectric inside them must shrink too. The study measured the permittivity of single nanopowders for that reason.
    - where: Lead-free piezoelectric ceramics
      line: A 2015 study reactively sintered BaTiO3 and reached a d33 of about 120 pC/N at 1300 °C. The authors call BaTiO3 a potential lead-free piezoelectric ceramic.
  can_do:
    - label: Curie point
      value: About 125 to 128 °C in a ceramic
      benchmark: curie_temperature
      line: A sintered ceramic in the 2015 study had a Curie temperature of about 125 to 128 °C at 10 kHz. The tetragonal phase of a single crystal ends at 132 °C in its datasheet.
    - label: Piezoelectric response
      value: About 120 pC/N
      benchmark: piezoelectric_d33
      line: Reactively sintered at 1300 °C for 2 hours, the ceramic reached a d33 of about 120 pC/N at about 85% relative density.
    - label: Permittivity
      value: 3000 along the a axis
      benchmark: dielectric_constant
      line: A single crystal has relative permittivity 3000 along the a axis and 800 along the c axis. The 2015 introduction quotes 1700 for BaTiO3.
    - label: Heat conduction
      value: 6 W/mK at 300 K
      benchmark: thermal_conductivity
      line: The single-crystal datasheet gives a thermal conductivity of 6 W/mK at 300 K.
    - label: Melting
      value: 1625 °C
      benchmark: melting_point
      line: The Stanford sheet gives a melting point of 1625 °C (2957 °F) for the powder.
  compare: The same oxide behaves very differently by form. The single crystal has permittivity of 800 to 3000 along its axes, the sintered ceramic is quoted at 1700 in the 2015 introduction, and a single nanopowder peaked at 60 in the 2024 single-particle measurement. Its melting point is 1625 °C for the powder, and the crystal datasheet's 1891 K (about 1618 °C) is close to that figure.
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Density
      benchmark: density
    - label: Curie point
      benchmark: curie_temperature
  handling:
    - Store dry and sealed, away from strong oxidizing agents and strong acids.
    - Avoid dust. Use an N95 or P1 dust mask for nuisance dust, and adequate ventilation for dust-forming work.
    - 'Exposure limits are given as barium: 0.5 mg/m3 in PubChem''s record and 0.01 mg/m3 or below as an Apollo exposure band.'
  good_for:
    - Capacitor dielectrics. Permittivity is high, and the 2024 study ties it to the MLCC design.
    - Lead-free piezoelectric elements well below the Curie point. A reactively sintered ceramic reached a d33 of about 120 pC/N.
  watch_out:
    - Curie point near 125 to 132 °C. Above it the piezoelectric and high-permittivity response is lost.
    - 'Density and strength: the reactively sintered ceramic was only about 85% dense, and no bending strength or toughness value was read.'
    - 'Acute toxicity: the powder is harmful if swallowed or inhaled.'
  verdict: Barium titanate is a high-permittivity, piezoelectric ceramic whose main limits are its Curie point near 130 °C and the acute toxicity of its powder. The sources read here cover its phase transition, permittivity and piezoelectric response, but they give no strength, space or radiation data.